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On Can Nuclear Power and Renewable Energy Learn to Get Along?

Hey gang: let's try not to question anyone's motives here and give people a respectful benefit of the doubt unless given reason otherwise. Joris, this was a pretty respectful comment, and I appreciate that, but I just wanted to caution on this going forward. Thanks,

Jesse

April 16, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Hi James, 

Thanks for the comment. I think you're probably right about the spectrum of storage costs and nuclear/renewable hybrids. That's something I hope to explore in future modeling work with a colleague here at MIT. 

Just to be clear: as I noted in the intro sentance, this post is focused on nuclear in combination with variable renewables like wind and solar, not more reliable sources like hydro, geothermal, or biomass.

Also, while solar better aligns with electricity demand than wind, that doesn't solve the integration issues with nuclear. If it reaches a penetration level where at mid-day, solar is producing close to 100% of load, nuclear will have to cycle off. Solar also is closer to peak, but not really on-peak. In nearly all regions, peak demand is experienced in late afternoon or early evening, not midday when solar systems are at 100%. So what we're seeing in some of the modeling around here (MIT) of high-penetration of solar is that the remainder of your system (i.e. excluding solar) becomes a "double peaking" system: you get a peak in late morning, then a big trough as solar ramps up around midday, then another sharper peak in the afternoon/evening as solar falls off and peak demand picks up. That actually increases rather than decreases the need for fast-ramping system capabilities. California regulators have dubbed this the "Duck Curve," while Jeff St. John calls the even more pronounced situation in Hawaii the "Nessy Curve" (both for their shapes). 

Cheers,

Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

"...the assertion that "ultra low" carbon emissions are required is of doubtful necessity"

There's no doubt for this column or this website! Climate change is a pressing global imperative. End of discussion on that matter.

Let's keep on topic. 

Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Hi Ben,

Thanks for the comment. I'll look again at the NREL Futures report which I included in the recommended resources at the end of my post. 

RE larger balancing/control areas, you are of course correct. As I noted in another comment, when I said "power system" in the post above, I meant the full interconnected, balanced system (i.e. a closed system). The larger that system, the more renewables you can get in there and the less correlated their output is likely to be. But once you get to an energy share equal to about their capacity factor, you certainly can see ramping from 0 to 100% of demanded energy on a regular basis, necessitating lots of storage/sinks/flexibility. So larger balancing issues helps renewables integration (or renewables-nuclear integration) as you say, but it doesn't really solve the problem.

Cheers,

Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Thanks for the comment Ed! Power to gas is actually what I had in mind when I wrote about "energy sinks" in the post. Desalination maybe also. But the example "energy sink" I linked to was actually Hydrogenics efforts to use excess power production during peak wind output/low demand days in Denmark to produce electroyltic hydrogen used to upgrade sewage gas into pipeline quality natural gas. It's a very interesting example of the kind of use of excess power we'd likely see much more of in a high-renewables or renewables-nuclear hybrid system.

Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Thanks for the thoughtful comment. Cheers,

Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Thanks Paul!

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

How do you support that bottom line though Alan? That sounds like an assertion, but it's not clear how that's the case. It's one thing to assert that the most economical low-carbon energy mix is all renewables. It's another to say that renewables and nuclear "don't really play well together, except in small doses." I think I've shown how they do, assuming you have storage/flexibility. And assuming you don't have storage/flexibility, an ultra-low carbon renewables dominated system itself isn't possible (except at extraordinary cost) due to necessary curtailment. 

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

I've not seen any technical literature on that question. But I'm talking with one of my colleagues here about doing some modeling to answer just that. This could make for a very interesting paper...

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Thanks for this excellent resource Robert! I just spent a while poking through this data set, which is really really helpful. It looks like today, France's aggregate nuclear output ramped up/down by 4.5 gigawatts already. That's about as much ramping as we saw from their (very flexible) hydro plants and about 4 times as much ramping as we've seen today from their entire coal and gas fleet. So clearly France has figured out how to operate their nuclear plants more flexibly than most anywhere else. The data is clear.

This PDF of a technical presentation from French utility EDF also discusses their flexible reactor operation. It even shows plants cycling off over weekends during low demand periods sometimes (see slide 8), although this obviously comes at a cost, and it does take a couple days to get back online after powering off fully. The slides do note a set of technical and operating challenges to modulating reactor output flexibly. Reactor operators need to be well trained to do this, but its certainly possible.

Cheers,
Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Hi Alan,

I grant that without lots of economic storage/sinks, you'd hit the cieling on renewables faster if you have a share of nuclear in the system as well. So if your goal is to increase renewables to their highest penetration before hitting their cieling before needing storage, then you'd want to back off of nuclear. But if your goal is to get to the lowest carbon power system as possible before needing storage, then I doubt that's the best way to go. 

Simple math here but I think this gets at the gist of it: if your system is say 20% nuclear, then you'd hit the renewables cieling roughly when their energy share = their capacity factor x (100% - nuclear's share). So for solar at 10% CF, you'd hit the cieling at 10% x (100% - 20%) = about 8% of the energy mix from solar instead of 10% if you had no nuclear in the system. For wind at 33% CF, you'd hit the cieling at 33% x (100% - 20%) = about 26% of the energy mix from wind instead of about 33% if you had no nuclear in the system.

So yes, you lose a few percentage points of renewables share if you have 20% nuclear in your system versus if you don't. But if carbon is your priority, it makes no sense to give up that 20% from zero-carbon nuclear in order to get 2% more solar or 7% more wind! 

So again: if you want an ultra low-carbon energy system with high penetrations of solar or wind, you need massive amounts of economic storage and sinks and DR. And if you have those, nuclear and renewables seem to work just fine together. And if nuclear and renewables aren't mutally exclusive, the lowest CO2 for the least money may very well be a hybrid system.

Jesse

April 15, 2014    View Comment    

On Can Nuclear Power and Renewable Energy Learn to Get Along?

Thanks Robert. I forgot about your great post in October on capacity factors and challenges for high penetrations of renewables (and nuclear). I highly recommend folks head over there to read it and then come back to join this discussion. Cheers,

Jesse

April 15, 2014    View Comment